The present invention relates to a method of transferring a device or devices such as semiconductor light-emitting devices, a method of arranging devices for transferring the finely processed devices to a wider region by application of the transferring method, and a method of manufacturing an image display system.
At present, electronic apparatuses or the like are manufactured with a multiplicity of fine devices, electronic component parts, electronic devices, electronic component parts obtained by embedding these devices in an insulator such as a plastic or a similar material. For example, in the case of arranging light-emitting devices in a matrix form to assemble an image display system, a method of forming the devices directly on a substrate has been adopted such as a liquid crystal display (LCD), a plasma display panel (PDP) or a method of arranging single LED packages as in the case of a light-emitting diode display (LED display).
Here, in the case of the image display system such as the LCD and PDP, the device cannot be isolated, so a method of forming the devices at intervals equivalent to the pixel pitch of the image display system from the beginning of the production process has generally been adopted.
In the case of the LED display, a method is used which takes out the LED chips after dicing, connects the individual LED chips to external electrodes by wire bonding or bump connection using flip chips, and then packages the LED chips. In this case, the LED chips are arranged at the pixel pitch of the image display system before or after the packaging, and the pixel pitch has no relation with the pitch at which the devices are formed.
Since the LEDs (light-emitting diodes), which are light-emitting devices, are expensive, a multiplicity of LED chips are produced from a single wafer, whereby the image display system using the LEDs can be manufactured at a lower cost. Namely, by forming the LED chips (conventionally about 300 μm square in size) in a size of about several tenths of a μm square and then connecting them to manufacture an image display system, the cost of the image display system is lowered.
In view of the above, one known method includes the steps of forming the devices at a high degree of integration, and moving the devices while spacing the devices further apart into a wider region by transferring or the like. Therefore, a comparatively larger display system such as an image display system is constituted. For example, in one known method shown in FIG. 21A, devices 93 are arranged on an adhesive layer 92 on a base substrate 91, and then, as shown in FIG. 21B, one of the devices 93 is taken out by use of a suction head 94, and is put on an adhesive layer 96 on another substrate 95.
In the case of manufacturing an image display system by the transferring method described above, the devices must be transferred securely. In addition, the devices must be transferred and with efficiency and a high degree of accuracy.
When the above-mentioned method is used, however, the transfer requires several steps, namely, taking-out or removing the device with the suction head, moving the device, and then mounting the device on a substrate, so that the transferring step is intricate. In addition, where the device to be transferred is a complex device, it is very difficult to take out only the desired device by such a method.
Besides, in an actual mounting machine, the positioning precision at the time of arranging the devices is limited to about 10 μm, and therefore, it is difficult to further enhance the positioning precision.